Organic Chemistry
by silvermyth
Summary: Lazy. Articulate. Enthusiastic. Hot. Zexion mentally ticked off the adjectives he'd accumulated for his chemistry professor, and tried to remember when he'd started using that last one. It was pointless and stupid to be infatuated with an instructor. Nothing would come of it except disappointment...


**A/N:** This is a secret Santa gift for tumblr user metakhfanonce. She wasn't particular, but we both agreed that there was a sad lack of Zemyx in the fandom. So here we are. There's also AkuRoku mentioned in passing (this could take place in the same AU as T.A.) and if you look hard enough, implied Xion/Namine, because why not. I'm really not sure what happened with this fic, it sort of just took off without me about halfway through. Anyway, I hope everyone enjoys!

 **Organic Chemistry**

"So, as I'm sure you all know, this is the last lab for the semester." Demyx smiled. "It's been great getting to know you guys, but if you're anything like me, you're probably ready for break, am I right?" The other students concurred with more enthusiasm than they'd shown all semester, smiling at each other and pumping fists.

Zexion fidgeted with his pen; he, for one, wasn't particularly looking forward to an icy month away from his studies. Even the thought of the upcoming holidays did nothing for him—Christmas was superfluous, New Year's nothing but an arbitrary date chosen to mark a full rotation of the planet. He would mark both holidays as he did every year: nose tucked in a book, and, if he was lucky, Lexicon purring in his lap. Well, at least he could enjoy that.

"Being that this is the last lab," Demyx continued, "I've simplified the procedure a little bit so you guys can get out of here faster." He grinned. "I wasn't lying when I said I'm ready for break. This shouldn't take you longer than an hour. If anyone's still here past four, I'm docking points for this lab, got it?"

Zexion rolled his eyes, but copied down the modified instructions anyway. His Orgo professor had been like this from the start, modifying labs to get them done quicker, threatening to dock points from students that made him stay in the lab any later than he had to or gave him extra work. Zexion had lost points on his first lab for "over-explaining," and from then on considered him one of the _lazy_ professors.

"Hey Zexion, you taking Orgo II next semester?"

Zexion looked up and blinked at his lab partner. "Yes."

"Awesome! Which section? Maybe we can be lab partners again."

A frown. "Demyx's again. Nine-forty." Lazy he may be, but Zexion would give credit where credit was due, and their professor's lectures were on-point (and often even entertaining), his grading criteria clear and fair.

"Me too! Yes, the dream team, reunited!" Zexion raised one silvery eyebrow and shrugged, before sweeping his long fringe up to pin it back. "Think we can have a perfect record and be the first to leave today, too?"

Zexion was already opening drawers and pulling out equipment. "Not if we don't get to work."

The redhead snorted and slid his safety glasses over his face. "Yeah, yeah."

Zexion had to admit, it was a point of pride when he and Axel approached Demyx, lab books in hand, before any of the other groups had finished. Demyx accepted them with his usual smile, flicking through their reports as they cleaned up their workspace and checked out lab equipment.

A week. That was all that was left until finals, and then winter break. A month of enforced solitude, even for an introvert, got boring fast. Every else had plans, though, and even his parents would be too busy at work for a trip home to be worth his time. Zexion scowled as he retrieved his graded lab book.

"Is there a problem, Zexion?" Zexion glanced up at Demyx's concerned face and fought off a blush of embarrassment, the scowl slipping from his mouth. He shook his head in the negative, fingers itching to pull out the pins holding his hair back so it could curtain his face. "Alright then. Good work, as usual. See you in class tomorrow!" Zexion nodded and made a beeline to his backpack, fumbling with the pins as he walked, until silky strands brushed his face, the familiar feeling soothing his hot cheeks.

Lazy. Articulate. Enthusiastic. Hot. Zexion mentally ticked off the adjectives he'd accumulated for his chemistry professor, and tried to remember when he'd started using that last one. It was pointless and stupid to be infatuated with an instructor. Nothing would come of it except disappointment, although he had to admit, the way he fixated on the cadence of the guy's voice during lectures made Orgo all the more interesting.

"Hey, Zex! Wait up!"

Zexion glanced over his shoulder at the tall redhead, pausing to let him catch up.

"I know you're probably already set for the exam, but you know, Roxas said he'd help with anything I was having trouble with, and you're welcome to join us."

Zexion let out a derisive huff. "Yeah, I'm okay, thanks."

Zexion stiffened as Axel threw an arm around his shoulders. "We were going to study over pizza. Or whatever. You know, we're both kind of broke, so maybe you could pitch in. Maybe Roxas and I can teach you something new." He waggled his eyebrows.

He shrugged the arm off with a glare. "I'm not feeding you."

Axel laughed. "Your loss, not mine! Anyway, see you tomorrow, yeah?" Zexion returned the redhead's departing wave half-heartedly. As friendly as Axel was, they weren't close, and anyway, he'd be splitting his time between work and Roxas over break. Zexion would only be a silent and invisible third wheel. He breathed a small sigh and turned his feet towards his apartment. One more week, and it would be just him and his little black cat.

o - o - o

Zexion frowned at his textbook, then glanced back at his answer to the problem, brow furrowing. His paper was already littered with eraser shavings, and, once he'd tired of erasing, scratched-out mistakes, and he still was having difficulty. _Just one problem_. Yeah, the chances that it would be on the test were small, and yeah, he could probably afford to lose a few points. But that wasn't the point.

He wasn't used to this feeling, not understanding a concept or problem, not being able to work through it on his own, and it was maddening. His hair was a mess, taking the brunt of his frustration as he alternated between pulling at his fringe and pushing it all back as he ran his fingers over his scalp. He had half a mind to text Axel to take him up on his offer, but dismissed the idea as soon as it surfaced.

He glanced at the time, then shuffled through his binder for his syllabus. If he hurried… Zexion slammed his textbook closed, earning a chorus of hisses and glares from the other students crammed into the library. He ignored them, stuffing his bag and shrugging on his coat. Demyx's office hours ended in half an hour, and the chemistry building was on the other side of campus. He didn't have time to worry about other students.

It was snowing when the library door closed behind him, and he glowered at the white flakes floating down around him, already forming a blanket on the sidewalk. It looked harmless enough, so he hastened forward, steps muffled. He managed to make it halfway to his destination before his foot found a slippery spot and he pitched forward.

Zexion cursed the cold and the snow and winter in general as he climbed back to his feet, dusting off. His palm stung—he'd scraped it in the fall—and the snow clung to his clothes stubbornly, melting as he continued, albeit with more caution. He checked the time and cursed the weather once more for good measure.

He was cold and damp and irritated when he stepped into the elevator and pressed the button for Demyx's floor. He tugged at his hair impatiently as the car traveled up, the numbers ascending until they reached the ninth floor, the doors sliding open with a smooth whoosh.

The floor was eerily silent as Zexion strode down the hall, office doors closed or sometimes half-open, but with a surprising absence of students, despite the threat of finals hanging in the air. Zexion's foul mood was quickly dropping and turning into anxiety as he neared Demyx's office.

He bit his lip when he came to a stop outside the door. It was closed, but he could hear muffled music from inside. He took a moment to catch his breath, studying the personality that covered the entrance to Demyx's office. It was decorated with cheesy posters full of science puns and humorous lab safety warnings, fliers for study abroad and internship opportunities. Zexion's lips turned up in a small smile at a particularly amusing one that sported a fringe of strips like an advertisement, Avogadro's number broken up to look like a telephone number.

Steeling himself, Zexion knocked timidly, uttering a tiny "Professor?"

After a moment, the door opened, Demyx's eyes widening when he saw who was behind it. "Zexion! I didn't expect to see you today!" He gave his student a quick once-over, taking in his ruffled state. "Is everything alright?"

Zexion tugged at his hair, hoping it hid the worst of his embarrassment. "I got stuck on problem five. From chapter eleven."

Demyx raised his eyebrows. "Yeah, okay, I can help you with that. Come in." He pulled the door open wider and gestured to a well-worn armchair on the near side of the desk. "Sit down. You got here just in time, I was just about to pack up. Anyway, I meant, you look like you had a bit of a rough time. What happened to your clothes?"

"Oh." Zexion sat gingerly on the chair, clutching his bag in his lap. "Yeah. It started snowing. I slipped." He made a face at the memory.

Demyx frowned. "You should be more careful."

Zexion stared down at his hands, nodding.

Demyx let out a small laugh. "Sometimes I worry, how do you see anything with all that hair in your face? But it suits you, you know?" He rifled through some papers on his desk. "I'm glad you pin it back in lab, at least, or it might've caught fire by now! Especially with that crazy redhead around. I've heard stories about that guy, let me tell you. Ahh, where is that damn review sheet?" He glanced up at the silent Zexion. "Do you have yours with you?"

Zexion nodded, digging his textbook back out, along with his notebook. "This one," he murmured, pointing.

Demyx leaned over to look at the problem. "Oh, _that_ one." He winked at Zexion. "Between you and me, that's not even going to be on the test. The course coordinator put it on there, but we told her it was too tough for you guys. It's not even something we really go into until Orgo II. You're taking that next semester, right?"

Zexion fixed one blue eye on the blond. "Yes. But that's not the point. I don't understand it. Whether it's on the test or not, it bothers me. So please explain it to me, Professor."

Demyx scratched the back of his neck. "You can call me Demyx. I'm still getting used to the whole 'Professor' thing, you know?"

He glanced at the clock, and then back to Zexion; Zexion followed the look, his face falling as he realized that office hours were officially over. And, Demyx being Demyx, was probably getting antsy to leave. He looked down at his feet. "Sorry, I didn't mean to waste your time, Prof—Demyx." He reached for his book. "I guess I'll just look it up—"

"Hey, hey!" Demyx put his hand over the book. "If it's you, I don't mind. I can't turn away my best student when he wants to learn more!"

Zexion tilted his head so his hair would fall to obscure his blush. "B-best?"

Demyx chuckled. "And modest! Okay, okay. So, what's tripping you up with this?"

Zexion explained his approach to the problem, and quickly found himself entranced by Demyx's slender hands and smooth voice as he worked through the problem step-by-step. He mentally ticked off his list of Demyx adjectives again: lazy, articulate, enthusiastic, hot, and added a new one to the list. Considerate.

Zexion beamed up at his professor. "Thank you, Demyx."

"No problem-o! I know it's a little selfish, but I really hoped you chose my section for Orgo next semester. It's such a pleasure to have someone like you in class." Zexion nodded, practically glowing at the praise. "Good! Well, of course you'll do well on the exam, so no worries there. What about break? You have anything fun going on?"

Zexion shrugged, and, realizing that Demyx was studying him, pulled at the ends of his fringe, avoiding the piercing gaze.

"I've never seen anyone so unenthusiastic for vacation," Demyx murmured. "Is there a problem at home? Well, you don't have to tell me if you don't want to, but if there's something wrong, you should at least talk to someone."

Zexion shook his head, peering out from behind his hair. "No problems." And, before he really thought about what he was doing, he added, "Just nothing to really look forward to." He glanced up at the clock again. "Sorry to have kept you late." He tucked his textbook into his backpack and zipped it.

"Zexion." Coat in hand, he turned to see Demyx's thoughtful expression. "Do you have anywhere to go during the break?"

Zexion opened his mouth, then closed it again and pulled his coat on. "I have an apartment."

Demyx crossed his arms. "That's not what I meant. Family? Friends?"

Zexion shrugged. "They're busy. It's no big deal. See you later." Bag in hand, he darted into the hall before Demyx could reply.

Once back in the safety of the elevator, Zexion banged his head against the metal wall. Of course Demyx would ask those questions. Some teachers cared about all of their students like that; there was nothing else behind it. Still, he had trouble reconciling that with his image of the professor in his mind, the Demyx that explicitly stated that his office hours ended at the posted time and no later. The Demyx that penalized students that made his job harder, and simplified labs to make less work for himself. He didn't seem like the go-above-and-beyond type, to Zexion.

o - o - o

Zexion put his pencil down and flipped through his test booklet one last time, checking over his answers. Satisfied, he gathered his coat and bag and took the test up, dropping it in the pile for his section. He turned to give Demyx a whispered "thank you," but the blond beat him to the punch.

"Zexion, can I talk to you for a minute?" He jerked his head towards the door, and Zexion obediently followed him out into the hall. "Look, it's not right to spend the holidays alone. So, if you want, you're welcome to come over to my place. My family likes to celebrate on Christmas Eve, but Christmas Day it's just me."

Zexion bit his lip and stared down at his shoes. "It's fine. Holidays aren't anything special."

"Well, in case you change your mind. Or if you're feeling lonely on a different day. You can call me." A slip of paper slid into Zexion's line of sight. "This is my cell number." Zexion stared at the numbers, not moving to take it. "Vacation should be fun, Zexion."

Zexion turned one blue eye up to look at his professor. Sincere. Another one to add to his list. And something else, that he couldn't put a finger on. "Okay." His fingers closed over the slip of paper.

Demyx's face lit up in a grin. "Good."

Zexion's lips curled up in an answering smile.

"Ah, well, I better get back in there, huh? Not everyone's a model student like you," Demyx teased. "Talk to you later!"

Zexion felt warm. Demyx's own number was in his hands. He swept his eyes across the digits again, committing them to memory.

The warmth and excitement retreated by the time he made it back to his apartment. It was just a phone number. Nothing more. Zexion wasn't special, not in the way he hoped. Just another teacher's charity case. Professors don't get involved with students, and Zexion, stupid, stupid, _stupid_. There was no room for that.

o - o - o

The first week unfolded in peace, days spent under the blankets with a book propped open on his pillow or in his lap, Lexicon sometimes joining him while he read, a warm, silent companion. He made the short walk to the supermarket at the end of it, to stock up on essentials, only to be forcefully reminded that Christmas was only a week out. Holiday sales and decorations, recipes, a Salvation Army bell-ringer stationed at the entrance of the store. Other customers with their carts heaped high with ham and turkey and stuffing.

His family had never celebrated Christmas, but he found himself staring at the holiday ham pictured in the store's mailer, wondering what it might be like to share a home-cooked meal with someone.

A certain blond someone who taught Organic Chemistry.

It snowed two days out from Christmas, and Zexion found himself staring out the window watching it fall. It made him feel cold and isolated, and ten numbers repeated themselves over and over in his mind, attached to a list of adjectives.

It was late when he dialed the numbers, and he didn't expect an answer, but Demyx's low, warm voice came over the line after a few rings, after all. "Hello?"

Zexion was quiet for a moment, before he realized he was required to talk. "D-demyx?"

"Zexion? Is that you?"

Zexion nodded, then cleared his throat. "Yeah."

"How's your break so far? Is everything alright?"

"It's okay." Even though he knew Demyx couldn't see him, he still found himself hiding his face behind his hair. "Can I…is it still okay, about Christmas?"

"Yeah, sure, of course! You live in town, right? I can come pick you up, if you like."

Zexion wrapped a strand of hair around his finger. "Okay."

"Alright, what's your address?" Zexion recited the apartment's street address. "Okay. Is ten okay?"

"Yes."

"I'll see you then! Did you want to talk about anything else while you've got me on the line?"

Zexion pondered the question. Did he? He was already feeling better, hearing Demyx's voice, and planning to hang out for Christmas. Anything more would be asking too much, really. "No, it's fine."

"Okay. I'll see you Christmas morning, then! Good night, Zexy."

"Thanks, Demyx. Good night." Once he'd hung up, Zexion bit his lip at the shortening of his name. 'Zex' he'd heard before, but never 'Zexy.' It was a very familiar way to address him, he decided, and wondered if he liked it.

If it was Demyx, he thought, it was okay.

o - o - o

Christmas morning dawned cold and bright, the sun glinting off of ice and fresh snow to blind Zexion as he peered out the window, watching for Demyx's car. A habitual early riser, he'd already been up long enough to shower and dress in jeans and an oversized sweater, and eat a modest breakfast. Demyx had called earlier to let him know he was on his way, and Zexion had been unable to stay still since. Lexicon, sensing something was up, wound around his legs, meowing for attention.

Zexion bent down to pet the black cat. "You'll be fine, don't worry. I'm coming back." He glanced up at the sound of an engine outside, and the subsequent ringing of his cell phone. "Hello?"

"It's Demyx! I'm here!"

Zexion didn't bother to tell him that the call had been unnecessary. "I'll be right out." He gave Lexicon one last pat on the head before shrugging into his coat and wrapping a scarf around his neck.

Demyx's car was a yellow four-door that had seen better days, but somehow, with the array of bumper stickers and music audible even with the windows closed, it suited him. The blond waved from behind the wheel, but Zexion's eyes slid to the the black-haired young woman in the passenger seat. He frowned, an expression he quickly hid by burying his face in his scarf. A girlfriend? Another student?

Perhaps it was a little vain, but he'd half-expected to be the only person sharing Demyx's company that day. Still, it wouldn't do to make a fuss. He hadn't been promised anything of the sort, after all.

Zexion climbed into the warm interior of the car, offering a polite "Hi" from the back seat. "Thanks for picking me up."

Demyx winked at him from the rearview mirror. "No, thank you for joining us! Zexion, this is Xion. Xion, Zexion."

The girl turned in her seat to face him, a small smile on her lips. "Nice to meet you." Zexion was struck by her eyes, a bright, forget-me-not blue that set off her delicate features. They were almost as beautiful as Demyx's, whose eyes he tried to catch in the mirror once more, to no avail, as they were already on the road.

"Yeah, nice to meet you," Zexion replied, only just loud enough to be heard above the noisy Christmas music. Pleasantries out of the way, he turned his attention to the scenery winding by the window. Fir trees in picture windows, snowmen standing guard on lawns, and candy-colored lights struggling to be noticed in the daylight. A gas station and a quaint shopping district, and then they were pulling into the parking lot of a modern apartment building.

Zexion reminded himself, not for the first time, that Demyx was just being nice, and that there was nothing special about spending a holiday with his professor. He put his list of adjectives aside as Demyx led him and Xion into the building, and instead just tried to be happy that he wasn't still sitting at home, by himself.

"This is the lobby," Demyx announced, unnecessarily. He waved at the front desk person, a tiny blond girl, whose face broke into a grin when she saw them. "And, concierge of the year, Miss Namine." Demyx paused to address the blond. "Namine, this is Zexion," Zexion waved at the acknowledgment. Demyx smiled down at the girl. "I'll have Xion bring you some food down later, okay hon?"

Namine beamed. "Yes, please!"

They departed with a "See you later!" and took a short elevator ride that ended with a few more steps to reach Demyx's door.

"Come in, Zexy, make yourself at home," Demyx urged, holding the door for him and Xion. Xion, he noticed, was quick to toe her shoes off and plant herself on a plush couch, flicking the TV and a game console on.

Zexion stepped in as his mood fell down a few notches. Whatever Xion was to Demyx, they were already familiar with each other. Zexion was an outsider—was that really better than being home alone? Still, it was too late to go back, so he left his shoes near Xion's as he glanced around the apartment. A small tinsel tree stood in front of the picture window, lights twinkling off and on, while garland framed doorways and bookshelves. The place itself was small, obviously not meant for more than one or two people, but tastefully decorated.

His brief appraisal finished, he looked up at Demyx expectantly.

Demyx brushed his shoulder as he crossed the wooden floor into the kitchen. "Can you cook? It'd be great to have some help in here, but I'm afraid Xion's kind of useless." He shot the girl a dark look across the room. "It's nothing fancy, really, we had a big dinner yesterday with the family, but I thought it would be nice, anyway."

Zexion shrugged. "Yeah, I can cook a little."

Demyx grinned. "Good! Why don't you take care of your hair? You have anything to clip it back with? A kitchen is just like a lab, you know! They don't call it 'kitchen science' for nothing!"

Zexion snorted and came back with a dry reply, "You don't say. Sorry, Professor, I didn't come prepared for class today." But a smile stretched across his features, Demyx's bright mood infecting him.

"Demyx! I'm not at work, and don't remind me of it," he wailed dramatically. "I'm on vacation! Now, maybe Xion can help you out. No one works in my kitchen without the proper kitchen safety apparel."

With a huff, Xion paused her game and fished around in a cutesy handbag to produce a handful of bright barrettes. "Here." She waited until Zexion retrieved them before returning to the game, little animated characters whizzing across the screen to cheerful background music.

Brows raised, Zexion pinned his hair back with practiced motions, until he was sure none of it would stray forward.

"Good, good. Now, here, do you think you can make this?" Demyx handed him a recipe card, and pointed to the ingredients laid out on the counter; Zexion nodded the affirmative. "Great! While you work on that, I'll start the chicken."

The late morning worked its way towards afternoon like that: Demyx directing Zexion as they prepared a full three-course meal, with Zexion interjecting more and more as he began to relax into his new surroundings, until the two were teasing each other at every opportunity. Xion had all but faded into the background when Zexion managed a particularly witty response to something Demyx had said. But he was sharply reminded when Demyx called over to the girl on the couch.

"Xion, can you take this down to Namine?"

Xion practically bounced up from the couch. "Of course! Looks good, Dem."

"Thanks. I had a great lab partner." He winked at Zexion, who couldn't stop the heat that rushed to his face.

Xion rolled her eyes as she backed out of the door. "You're a giant dork."

Demyx grinned. "Yep!" Once the door closed, he turned to Zexion and gestured at the food they'd set out. "Dig in."

Zexion glanced back at the door. "Shouldn't we wait for Xion to come back?"

Demyx burst out laughing. "Xion? No, she's going to be bugging Namine for at least an hour."

Zexion fiddled with one of the clips in his hair. "Oh. I thought she was…" he trailed off, still not sure what he'd thought she was doing there with them, since she'd spent the whole morning playing video games.

"Oh, right! I didn't tell you. Xion's my little cousin. She comes over to play my video games and harass my concierge. She's a sweetheart, though."

"Oh."

"'Oh,' he says." Demyx's face turned serious. "Zexion, what are you thinking? You've gone all quiet, but you can't hide behind your hair. I can practically see the gears turning in your head."

Zexion studied the grain of the wood flooring, until two sock-clad feet entered his vision.

"Are you having fun, Zexy?" he murmured. "Did you want to do something else, while you're here?" The tone was careful, conversational, the innuendo only barely in the words themselves, so Zexion couldn't really be sure he'd actually heard it, rather than wished it.

When Zexion's silence stretched on, Demyx sighed and stepped back. "Well. Anyway, I hope you'll enjoy the food, at least." When Zexion looked up, Demyx had a crooked smile on his face, though his eyes were tinged with something a little less cheerful.

Zexion pursed his lips and took a breath before retorting, "Of course I will. I helped make it, after all."

Demyx's smile grew hopeful. "There he is. I was a little worried you'd left me."

Zexion studied his host. "Demyx? Why did you invite me?"

Demyx frowned. "I wanted to make sure you were happy over break. You looked pretty bummed at the end of the semester."

 _Well_. Zexion ran down his list of Demyx adjectives, and then replayed the morning in his mind. It would be a risk to say something but…a calculated risk, he decided. He closed the distance Demyx had put between them. "Aren't you a chemist?" At Demyx's perplexed look, Zexion grinned. "This is the part where we add the catalyst. Because, if you want to make me happy, you'll kiss me." Surprised at his own burst of audacity, Zexion bit his lip and watched as Demyx processed his words.

Finally, Demyx cursed and bent to kiss him, an electric brush of lips that stole Zexion's breath. When they pulled apart, the blond had a ridiculous grin on his face. "I wasn't sure!" He startled Zexion with a tight bear hug. "Best Christmas present ever!"

Still held in Demyx's arms—not a bad situation, he decided—Zexion raised an eyebrow. "I don't celebrate Christmas."

Demyx laughed. "But I do!" He released Zexion. "And, my Christmas present to you is, as many kisses as you want!"

Zexion felt his face heat up. "O-okay."

"But to make it official. Zexion, will you have dinner with me?" Zexion quickly committed the eager face to memory.

"Didn't I already say I would?" Zexion smirked and began unclipping the barrettes holding his hair back.

Once the silvery hair was free, Demyx reached forward to brush it back again. "Thank you, Zexion."


End file.
